Aaaand then the four of them take over the changeling hive. Because I'm pretty sure Chrysalis isn't capable to dominating the minds of the for most powerful ponies in Equestria... and if Cadance was made into a changeling, her status as the alicorn of love would probably put her in some sort of infinite power loop or something.

Also...Changeling!Twilight: "Hey Chrysalis, guess what? That brainwashing spell of yours didn't work. So, I'm a Changeling now, but I STILL hate you, we're STILL sworn enemies, and now I have all the power of my Alicorn self, PLUS it's fueled by my love for my friends and family! So...I win!! Bye, send me a postcard from Tartarus!"

Changeling!Twilight: You know what you got wrong, Chryssie? You thought that spell of yours would isolate me, that it'd turn all my friends and family against me. Well, what a bunch of bull that was. They accept me no matter what. I'm a changeling now, but you, YOU'RE the one who's ugly, inside and out!"